1. Field of the Invention
The present invention relates generally to thin film magnetic heads used to read and write information to a magnetic storage medium and, more particularly, to a merged-pole magnetic head having inverted write elements.
2. Background Art
Multi-channel magnetic heads are used in tape drives to read and write information to a magnetic tape while the tape travels in both directions relative to the head. Known head designs use thin film processes such as micro-lithography, evaporation, sputtering, ion milling, electroplating, and wet etching to produce magnetic micro-structures on one side of a substrate such as SiC, AlTiC, and ferrite. For example, a number of head architectures use thin film technology to pattern write and read elements onto a substrate, which are then subsequently machined into head bumps and glued together to align the write and read elements for bi-directional tape motion. FIG. 1 illustrates an example of a xe2x80x9ctwo bumpxe2x80x9d magnetic head 10 formed in this manner, and FIG. 2 illustrates an example of a xe2x80x9cthree bumpxe2x80x9d magnetic head 20. An xe2x80x9cRxe2x80x9d is used to denote a read element, and a xe2x80x9cWxe2x80x9d is used to denote a write element, and respective gap lines are shown as dashed lines 12.
In order to write information onto a tape, read elements must be located so as to follow the track on the tape being recorded by the write elements. This is known as a read-back check and is used to ensure integrity of information written to the tape. Thus, write and read elements operate simultaneously. Unfortunately, the read channel detects unwanted noise from the write channel, which is commonly referred to as feed through. For this reason, write and read elements are kept separated from each other by a spacing denoted xe2x80x9cdxe2x80x9d.
In addition to the spacing requirement, each read element (R) must be precisely aligned with a corresponding write element (W) as shown by the dashed line axe2x80x94a, i.e., the xe2x80x9cbump-to-bumpxe2x80x9d alignment. Proper alignment is essential in order to enable the head to be capable of xe2x80x9cread-while-writexe2x80x9d (RWW) operation to verify that the information has been written to the tape correctly as the tape is spooled through the head.
It is anticipated that future storage media such as tape will attain storage capacities in excess of 1 terabyte of information. Such a high storage capacity places significant demands on tape drives and will be achieved, in part, through a significant increase in track densities of the tape. This increase in track density means that not only will the multi-channel recording head have to write and read narrow track widths, but also that the servo system must correctly align the head relative to the tape during both read and write operations. This necessitates that the tape drive meet track mis-registration requirements, which includes, among other factors, the read and write width tolerances and head and tape dimension tolerances. As track densities are increased, all head designs require increasingly stringent alignment between the write and read elements in both the forward and reverse directions, i.e., the bump-to-bump alignment.
FIG. 3 illustrates a block diagram of a conventional two bump head 30 having a merged-pole read/write element structure. Head 30 meets some of the demands placed by increased track densities. Head 30 includes two modules 32 and 34 positioned back-to-back with respect to each other. Each module 32 and 34 includes a substrate 36 and a merged-pole read/write structure facing outwards. Each merged-pole read/write structure includes a read element 38 positioned on substrate 36 and a write element having a wide top write pole 40 and a bottom write pole 42. Wide top write pole 40 is used to write information to tape. In operation, information is written by top write pole 40 of module 32 and then read verified using read element 38 of module 34 in a first tape direction indicated in FIG. 3. Similarly, information is written by top write pole 40 of module 34 and then read verified using read element 38 of module 32 in the opposite tape direction.
A problem with conventional two-bump head 30 with its merged-pole read/write structure is that significant offset between the width of wide top write pole 40 and the width of the track of the tape occurs. This is exacerbated for narrow track widths and, depending on tape media type, substantial erased zones at each edge of the track are formed. Both of these factors can greatly limit the head width tolerance impacting the TMR budget.
Accordingly, it is an object of the present invention to provide a merged-pole magnetic head having inverted write elements.
It is another object of the present invention to provide a magnetic head having a merged-pole read/write element structure with inverted write elements.
It is a further object of the present invention to provide a merged-pole multiple bump magnetic head having inverted write elements.
It is still another object of the present invention to provide a merged-pole magnetic head having write elements in which an inverted pole is used to write information.
In carrying out the above objects and other objects, the present invention provides a magnetic head for writing and reading data on a tape. The magnetic head includes first and second substrates each having first and second surfaces. The first surfaces of each substrate being connected with each other, the second surfaces of each substrate having a read element and an inverted write element. Each read element being formed over the second surface of each substrate and each inverted write element is formed over a respective read element.
Each inverted write element includes a write gap in a zero throat region and a top write pole disposed adjoining the write gap in the zero throat region. The top write pole has a top write pole width in the zero throat region. A bottom write pole is disposed adjoining the write gap in the zero throat region on a side of the write gap opposite the top write pole. The bottom write pole has an upper portion adjoining the write gap and a lower portion. The upper portion having an upper portion width in the zero throat region. The lower portion having a lower portion width in the zero throat region. The lower portion width being greater than the upper portion width and smaller than the top write pole width.
The write gap has a write gap thickness and the upper portion of the bottom write pole has an upper portion thickness. The write gap and the upper portion of the bottom write pole may be arranged so that the upper portion thickness is at least twice the write gap thickness.
Each inverted write element may further include a base disposed adjacent the bottom write pole on a side opposite the write gap, and a planarization layer disposed between the base and the write gap. Each inverted write element may further include a coil disposed adjoining the write gap on a same side of the write gap as the top write pole.
Further, in carrying out the above objects and other objects, the present invention provides a method of fabricating a magnetic head. The method includes forming a read element on a first surface of respective first and second substrates. A bottom write pole is then formed over each read element. Each bottom write pole has an upper portion and a lower portion in a zero throat region. A write gap is then formed overlaying each bottom write pole and a top write pole is formed overlaying each write gap. Each top write pole has a top pole width in the zero throat region that is greater than the lower portion width of the respective bottom write pole. Second surfaces of the first and second substrates together are then connected together.
Forming each bottom write pole may include depositing a bottom write pole layer, patterning the bottom write pole layer to define the upper portion of the bottom write pole disposed on a remainder layer, and patterning the remainder layer to define the lower portion of the bottom write pole.
Alternatively, forming each bottom write pole may includes depositing a bottom write pole layer, patterning the bottom write pole layer to define an intermediate bottom write pole, and patterning the intermediate bottom write pole to define the upper portion and the lower portion of the bottom write pole.
The method may further include depositing a planarization layer overlaying the bottom write pole prior to forming the write gap, and lapping the planarization layer to expose the upper portion of the bottom write pole in response to depositing the planarization layer. In this case, forming each bottom write pole includes forming an upper portion thickness to a target value and the method may further include lapping the planarization layer and the bottom write pole to reduce the upper portion thickness to a final value in response to lapping the planarization layer to expose the upper portion of the bottom write pole.
The method may also include measuring the upper portion width of the bottom write pole in the zero throat region to produce an actual upper portion width prior to forming the write gap, and stopping fabrication in response to the actual upper portion width being out of tolerance.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description when taken in connection with the accompanying drawings.